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208 results on '"Chen, D. Z."'

11. A hierarchical decomposition scheme for the topological synthesis of articulated gear mechanisms

Author

Chen, D.-Z. and Liu, C.-P.

Subjects
Decomposition (Mathematics) -- Usage, Topology -- Analysis, Gearing -- Analysis, Engineering and manufacturing industries, Science and technology
Abstract

An efficient methodology for the topological synthesis of articulated gear mechanisms (AGMs) is presented. A hierarchical model is developed to represent the structural topology of an AGM in which sub-systems in the bottom level are used as design primitives. By a proposed partition algorithm, design specifications are decomposed along the model to determine the attributes of the sub-systems in each level. The decomposition results in a composition polynomial that symbolically reveals all structural compositions of desired mechanisms. With the polynomial and the database of design primitives, the number of admissible mechanisms for a given design specification can be derived and all possible graph representations can be efficiently enumerated. Two 3-dof examples are presented for illustration.

Published
1999

14. Regulation of signal transduction pathways by peptide toxins

Author

Holmes, C. F. B., primary, Craig, M., additional, McCready, T. L., additional, Boland, M. P., additional, Dawson, J. F., additional, Chen, D. Z. X., additional, Wang, K., additional, Klix, H., additional, Luu, H. A., additional, Magoon, J., additional, O’Connor-McCourt, M., additional, and Andersen, R. J., additional

Published
1994
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16. BMSCs attenuate hepatic fibrosis in autoimmune hepatitis through regulation of LMO7-AP1-TGFβ signaling pathway.

Author

CHEN, Z.-K., CHEN, D.-Z., CAI, C., JIN, L.-L., XU, J., TU, Y.-L., HUANG, X.-Z., XU, J.-L., CHEN, M.-Z., XUE, F.-B., LAN, X.-L., WANG, X.-D., CHEN, Y.-P., SUN, H.-L., and GE, Y.-L.

Abstract

OBJECTIVE: In a previous study, we reported that transplantation of bone mesenchymal stem cells (BMSCs) significantly attenuated liver damage in a mouse autoimmune hepatitis (AIH) model. Moreover, expression of the LIM domain protein, LMO7, correlated positively with the invasive capacity of hepatoma cells. However, whether LMO7 plays a role in inflammation and fibrosis of AIH remains unknown. This investigation aimed to explore the effect of BMSC transplantation on LMO7 and the role of LMO7 in hepatic fibrosis. MATERIALS AND METHODS: S100-induced murine AIH and LPS-induced hepatocyte injury models were successfully established. Three doses of BMSCs were injected into AIH mice via the tail vein. LPS-treated AML12 cells were co-cultured with BMSCs in vitro. Small interfering (si) LMO7 RNA and T5224 (a specific inhibitor of AP-1) were used to demonstrate the relationship between LMO7-AP1-transforming growth factor (TGF)-β. RESULTS: Pathological examination and serum alanine and aspartate aminotransferase levels indicated that liver damage was notably ameliorated in the BMSC-treated mice. LMO7 level was upregulated, while AP-1 and TGF-β levels were downregulated upon intervention with BMSCs. AP-1 expression was upregulated in the siLMO7 group, whereas TGF-β level was downregulated in the T5224 group when compared to those in the control group. CONCLUSIONS: BMSC transplantation significantly limits liver fibrosis and upregulates the expression of LMO7. LMO7 inhibits the TGF-β pathway by inhibiting AP-1. This implies that BMSCs are a potential means of treating liver fibrosis. This approach has important implications for the treatment of AIH and other fibrotic diseases. [ABSTRACT FROM AUTHOR]

Published
2021

17. LncRNA FOXD2-AS1 accelerates the progression of cervical cancer via downregulating CDX1.

Author

CHEN, D. -Z., WANG, T. -F., DAI, W. -C., XU, X., and CHEN, P. -F.

Abstract

OBJECTIVE: To uncover the role of FOXD2-AS1 in aggravating the progression of cervical cancer (CC) by negatively regulating caudal-related homeobox 1 (CDX1). MATERIALS AND METHODS: FOXD2-AS1 levels in CC tissues with different tumor sizes and tumor staging were detected. Meanwhile, FOXD2-AS1 levels in CC patients either with vascular invasion, lymphatic metastasis or not were detected. Survival analysis on CC patients expressing high level or low level of FOXD2-AS1 was conducted by introducing the Kaplan-Meier method. After the silence of FOXD2-AS1, proliferative changes in SiHa and HeLa cells were assessed through cell counting kit-8 (CCK-8) and 5-Ethynyl-2'-deoxyuridine (EdU) assay. Subcellular distribution of FOXD2-AS1 in CC cells was analyzed. Next, CDX1 level in CC tissues and para-tumor tissues was determined. The potential correlation between CDX1 level and FOXD2- AS1 level was evaluated by the linear regression analysis. At last, the regulatory effects of FOXD2-AS1/CDX1 on the proliferative ability of CC were examined. RESULTS: FOXD2-AS1 was upregulated in CC tissues relative to those of para-tumor tissues, especially in those with larger tumor size and advanced tumor staging. Its level was not correlated to vascular invasion and lymphatic metastasis of CC. CC patients expressing a high level of FOXD2-AS1 suffered worse prognosis than those with low level. The silence of FOXD2- AS1 attenuated SiHa and HeLa cells to proliferate. FOXD2-AS1 was found to be mainly enriched in the nucleus. CDX1 was downregulated in CC tissues and its level was negatively regulated by FOXD2-AS1. The silence of CDX1 could reverse the regulatory effect of FOXD2-AS1 on the proliferative ability of CC cells. CONCLUSIONS: FOXD2-AS1 is upregulated in CC and its high level predicts a poor prognosis of CC patients. It accelerates the malignant progression of CC via negatively regulating CDX1 level. [ABSTRACT FROM AUTHOR]

Published
2019

20. Network of minima of the Thomson Problem and Smale's 7th problem

Author

Mehta, D., Chen, J., Chen, D. Z., Kusumaatmaja, H., and Wales, D. J.

Abstract

The Thomson problem, arrangement of identical charges on the surface of a sphere, has found many applications in physics, chemistry and biology. Here, we show that the energy landscape of the Thomson problem for N particles with N=132, 135, 138, 141, 144, 147, and 150 is single funneled, characteristic of a structure-seeking organization where the global minimum is easily accessible. Algorithmically, constructing starting points close to the global minimum of such a potential with spherical constraints is one of Smale’s 18 unsolved problems in mathematics for the 21st century because it is important in the solution of univariate and bivariate random polynomial equations. By analyzing the kinetic transition networks, we show that a randomly chosen minimum is, in fact, always “close” to the global minimum in terms of the number of transition states that separate them, a characteristic of small world networks.

Published
2016

25. ON A SUBCLASS OF CLOSE-TO-CONVEX FUNCTIONS

Author

WANG, Z.-g. and CHEN, D.-z.

Subjects
Statistics and Probability, Analytic functions,Starlike functions,Close-to-convex functions,Hadamard product (or convolution),Subordination between analytic functions,2000 AMS Classification: 30 C 45, İstatistik ve Olasılık
Abstract

In this paper, we introduce a new subclass Ks(λ, A, B) of close-toconvex functions. Such results as inclusion relationships, coefficient estimates, distortion and covering theorems for this class are proved. The results presented here would provide extensions of those given in earlier works. Several other new results are also obtained.

Published
2014

27. A Langmuir Probe System for the Test Setup of an RF-driven Negative Hydrogen Ion Source at HUST.

Author

Zhao, P., Chen, D. Z., Li, D., and Zuo, C.

Subjects
*LANGMUIR probes, *HYDROGEN ions, *ION sources, *PARAMETER estimation, *PLASMA density
Abstract

A test setup of an RF-driven negative hydrogen ion source is being constructed at HUST. It is operated at the typical pressure of 0.3 Pa, maximum RF power of 20 kW/1 MHz, with discharge pulse of 6-10 seconds. In order to diagnose the plasma parameters and evaluate the source performance, a highly integrated and automated Langmuir probe system has been developed in-house. It allows for multiple sweeping, mass data acquisition and automatic data evaluation in a fast diagnosis shot of several hundred milliseconds. Various analysis methods are investigated and compared for the ion density determination. Due to the low density and thick sheath in the plasma, OML theory is selected as the applicable one. Preliminary discharge and diagnosis experiments have been carried out in the experimental source. The plasma in the driver exhibits non-Maxwellian electron energy distribution with low density of 1017 m-3 and electron temperature of 59 eV at 20 kW/0.3 Pa. [ABSTRACT FROM AUTHOR]

Published
2017
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31. Damage analysis of particulate polymer composites based structure by using micro-meso-macro finite element approach

Author

Tang, C. Y., Tsui, C. P., Chen, D. Z., Uskoković, Petar, Fan, Jian-Ping, Xie, Xiao-Lin, and Lee, Eric Wai-Ming

Subjects
particle, polymer composites, finite element, micro-meso-macro approach, debonding
Abstract

A micro-meso-macro finite element approach has been developed for simulating the macro-scale damage coupled deformation in a particulate polymer composite (PPC) based structure under tension. A damage model for the PPC structure was developed to define the debonding damage behavior of the structure. The computational results determined in our previous studies by using finite element meso-cell modeling technique were used as the input parameters of the damage model and definition of the constitutive behavior of PPC. A user-defined subroutine VUMAT describing the damage-coupled constitutive behaviour of PPC for defining the material properties of the finite elements for the structure was then built and incorporated into the ABAQUS finite element code. A case example has been given to demonstrate the proposed approach. The macro-scale damage process in the simulated component was found to be reasonable.

Published
2006

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